Medical sensors can be implanted into the human body to retrieve diagnostic data regarding certain bodily functions. For example, pressure sensors located within the vascular system of the body can measure blood pressure at various locations within the body. FIG. 1 illustrates a representative sensor assembly 2 having a sensor 4 and a compressible retention member 6 positioned within a blood vessel 8. The sensor 4 is a self-contained device, having its own power supply and communication circuitry for communicating data to a remote device. Sensors of this type can be implanted into the body by inserting a catheter into the body and moving the catheter through the cardiovascular system until the end of the catheter is positioned at the desired implant location. The sensor can then be fed through the catheter and positioned within the appropriate blood vessel.
Due to the nature of the human body, portions of the vascular system through which the catheter is navigated can have relatively acute radii, and thus the catheter may be required to make one or more turns within the body before reaching the desired implant location. Thus, any sensor that is fed through the body must be small enough to negotiate any turns in the catheter when it is positioned within the body. This size limitation impacts the size of the power supply contained within the sensor and correspondingly, impacts the life of the power supply and thus the amount of time that a sensor can function within the body. For example, a sensor may have a power supply with a rated life of 10 years under normal use, including periodic recharging. It is not desirable to replace sensors of this type within the body. Therefore, it is desirable to be able to extend the length of time that diagnostic data can be retrieved at a given site without requiring replacement of sensors. What is needed, then, is a way to measure diagnostic data at a given site for longer periods of time, given the constraints of size on diagnostic sensors.